1. Field of the Invention
The invention relates to a method and apparatus for control of an electronic system, in particular a mobile data recording and data display appliance, in which the electronic system has a processor, control software and at least one input/output unit with a control unit, in which the processor is connected with the control software and the control unit, and the control unit is connected with the control software and at least 1 input/output unit, and in which to initiate processing cycles, the processor receives an initial cycle signal via an initial oscillator cable.
2. Description of Related Art
Most current microprocessors and computers normally possess an energy saving device incorporated into the individual processor chip. This relates to hardware and relevant software components, using which the microprocessors or computer are switched during operation to differing operating modes with reduced energy consumption. One should mention particularly energy saving operating modes: reduction of oscillator frequency, sleep-mode, software standby-mode and hardware standby-mode. Energy saving forms of operation mentioned are not run by all microprocessors. The energy savings thereby achieved vary between approx. 10% and over 90% of the energy consumed by the computer in normal operating mode.
Many microprocessors incorporate automatic adjustment of the oscillator frequency, by which the microprocessor is controlled. If it is necessary for the microprocessor to develop full capacity, the oscillator frequency is 100% of the maximum oscillator frequency. If the requirement of the microprocessor is less, the oscillator frequency is reduced appropriately. But the energy consumption of the microprocessor is only reduced to a minor extent. However, the advantage of this form of operation is that it is possible to switch between forms of operation with differing oscillator frequencies, without having to restart the microprocessor. This prevents interruption of the running of application programmes using the microprocessor when switching to an energy saving mode.
What is known as the sleep-mode gives increased energy saving. This mode produces a reduction in energy consumption of approx. 30%. However, when switching to an energy saving mode, the sleep mode requires an execution break for each application programme running on the microprocessor at the time of switchover. If a computer is in "sleep-mode", no processor capacity and no screen function is available. Normally this mode is terminated by pressing any key of the computer. After this key is pressed, the computer "reawakens". If a switch is made to sleep-mode whilst an application programme is being run on the computer, the running of this application programme is continued after the key has been pressed by the user. In this way the programme sequence is continued at the point at which the programme run was previously interrupted.
A significantly increased saving of energy (&gt;90%) is achieved with the "software-Standby" mode. Like the "Sleep-mode", on switching to the software standby-mode the execution of all application programmes running is halted. During this time the computer is not available for a user. This applies in particular to the computer screen. Normally the content of some of the registers of the microprocessor and also some of the content of internal memories of the microprocessor are retained in the software standby-mode. In order to terminate the software standby-mode and after breaking off this mode to continue processing of application programmes at the point at which the programme was previously interrupted, additional software routines are necessary.
In a further energy saving mode the energy consumption of the microprocessor is reduced to virtually zero. This is the hardware-standby mode. Unlike the sleep-mode and software-standby mode, application programmes, whose run was interrupted by switching to the energy saving mode are not continued at the point at which they were interrupted. In the hardware-standby mode one loses in particular the content of the microprocessor registers. If the hardware-standby mode is to be terminated and running of application programmes using the computer is to be recommenced, a time consuming rebooting of the computer is necessary. If the content of the microprocessor registers was saved in external memories before the occurrence of the hardware-standby mode, one has to accept a noticeable delay time when continuing the interrupted application programmes.
Consequently it is the task of the present invention to create an improved facility for energy saving operation of a microprocessor or computer.